Layoffs actually tend to artificially deflate stock prices as it's seen as a signal of a company in financial distress - this is actually one of the reasons why industries tend to do layoffs simultaneously across multiple corporations. Of course this can be used to turn a profit through short selling but you'd need to have some sort of prior knowledge to set up the short positions prior to the layoffs being announced.

Oh wow, you're right, why the heck did I think it was the opposite? I've been misusing that word for years. Thanks for letting me know!